package ServletDicUpDown;

/**
 * @author 李某
 * * @date 2021/11/20
 * *物有本末，事有终始。知其先后者，则近道矣！
 * *荷花开满池塘的前一天还是半塘荷花半塘云。
 */



import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


    /**
     * Servlet implementation class UploadServlet
     */
    @WebServlet("/UploadServlet")
    public class UploadServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;

        // 上传文件存储目录
        private static final String UPLOAD_DIRECTORY = "upload";

        // 上传配置
        private static final int MEMORY_THRESHOLD   = 1024 * 1024 * 3;  // 3MB
        private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
        private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB

        /**
         * 上传数据及保存文件
         */
        @Override
        protected void doPost(HttpServletRequest request,
                              HttpServletResponse response) throws ServletException, IOException {
            // 检测是否为多媒体上传
            if (!ServletFileUpload.isMultipartContent(request)) {
                // 如果不是则停止
                PrintWriter writer = response.getWriter();
                writer.println("Error: 表单必须包含 enctype=multipart/form-data");
                writer.flush();
                return;
            }

            // 配置上传参数
            DiskFileItemFactory factory = new DiskFileItemFactory();
            // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
            factory.setSizeThreshold(MEMORY_THRESHOLD);
            // 设置临时存储目录
            factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

            ServletFileUpload upload = new ServletFileUpload(factory);

            // 设置最大文件上传值
            upload.setFileSizeMax(MAX_FILE_SIZE);

            // 设置最大请求值 (包含文件和表单数据)
            upload.setSizeMax(MAX_REQUEST_SIZE);

            // 中文处理
            upload.setHeaderEncoding("UTF-8");

            // 构造临时路径来存储上传的文件
            // 这个路径相对当前应用的目录
            String uploadPath = request.getServletContext().getRealPath("./") + File.separator + UPLOAD_DIRECTORY;


            // 如果目录不存在则创建
            File uploadDir = new File(uploadPath);
            if (!uploadDir.exists()) {
                uploadDir.mkdir();
            }

            try {
                // 解析请求的内容提取文件数据
                @SuppressWarnings("unchecked")
                List<FileItem> formItems = upload.parseRequest(request);

                if (formItems != null && formItems.size() > 0) {
                    // 迭代表单数据
                    for (FileItem item : formItems) {
                        // 处理不在表单中的字段
                        if (!item.isFormField()) {
                            String fileName = new File(item.getName()).getName();
                            String filePath = uploadPath + File.separator + fileName;
                            File storeFile = new File(filePath);
                            // 在控制台输出文件的上传路径
                            System.out.println(filePath);
                            // 保存文件到硬盘
                            item.write(storeFile);
                            request.setAttribute("message",
                                    "文件上传成功!");
                        }
                    }
                }
            } catch (Exception ex) {
                request.setAttribute("message",
                        "错误信息: " + ex.getMessage());
            }
            // 跳转到 message.jsp
            request.getServletContext().getRequestDispatcher("/message.jsp").forward(
                    request, response);
        }
    }

